JP2648568B2 - Method for forming dye ablation image - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION This invention relates to the use of high molecular weight binders in laser dye ablative recording elements.

[0002]

2. Description of the Related Art Recently, a thermal transfer apparatus for obtaining a print from an image generated electronically from a color video camera has been developed. According to one method of obtaining such prints, an electronic image is first subjected to color separation by a color filter. Next, each color separation image is converted into an electric signal. Thereafter, these signals are manipulated to generate cyan, magenta, and yellow electrical signals, and these electrical signals are transmitted to a thermal printer. To obtain a print, a cyan, magenta or yellow dye-donor element is placed face-to-face with a dye-receiving element. The two are then inserted between the thermal print head and the platen roller. Heat is applied from the back side of the dye-donor sheet using a line-type thermal printhead. Thermal printheads have a number of heating elements and are heated up sequentially in response to cyan, magenta or yellow signals. The process is then repeated for the other two colors. Thus, a color hard copy corresponding to the original image viewed on the screen is obtained. Details of this method and the apparatus for performing it are described in U.S. Pat. No. 4,621,271.

Another method of using the electronic signals described above to obtain prints thermally is to use a laser instead of a thermal printhead. In such a manner, the donor sheet contains a substance that exhibits strong absorption at the wavelength of the laser. Upon irradiation of the donor, the absorbing material converts light energy into thermal energy, which transfers the heat to the nearby dye, which is heated to its evaporation temperature and transferred to the acceptor. The absorbing material may be present in the layer below the dye, or mixed with the dye, or both. The laser is modulated by an electronic signal representative of the shape and color of the original image, heating and evaporating each dye only in those areas on the receptor that must be present to reconstruct the color of the original object . The details of this method are described in GB-A-2,083,726.

[0004] In one ablative mode of imaging by the action of a laser beam, an element in which a dye layer composition comprising an image dye, an infrared absorbing material, and a binder is coated on a support, the element is dye-sided. From the image. The energy provided by the laser drives out the image dye at the spot where the element's laser beam hits, leaving the binder behind. In ablative imaging, laser irradiation causes material to be expelled from the layer by causing rapid local changes in the imaging layer. What distinguishes this from other mass transfer methods is the complete physical change (eg, melting,
Some sort of chemical change (e.g., bond breaking) rather than evaporation or sublimation) causes the image dye to transfer almost completely, rather than being partially transferred. The transmission D-min density value is useful as a measure of the completeness of laser separation of the image dye.

US Pat. No. 5,171,650 relates to an ablation transfer type image recording method. In this method, an element containing a dynamic release layer overcoated with an ablative carrier topcoat is used. The image is transferred to another adjacently aligned receiving element. Useful images obtained in this manner are contained on a receiver element.

[0006]

The above method has the problem that another receiving element is required. It is an object of the present invention to provide Dm obtained in a dye ablative recording element.
It is to provide a method for improving the in value. Another object of the present invention is to provide a single sheet method that does not require a separate receiving element.

[0007]

SUMMARY OF THE INVENTION These and other objects are achieved by the present invention. The present invention is a method for forming a monochromatic dye ablation image in which D-min is improved, which includes a step of imagewise heating using a laser. Dye ablative recording elements include a support having on its surface a dye layer containing an image dye dispersed in a high molecular weight binder in combination with an infrared absorbing material. Laser irradiation is performed through the dye side of the element. The ablated image dye material is removed to obtain an image in the dye ablative recording element. The high molecular weight binder is
100,00 as determined by size exclusion chromatography
It has a polystyrene equivalent molecular weight of 0 or more.

The term “polystyrene equivalent molecular weight as determined by size exclusion chromatography” is a well-known technique,
For example, F. W. Billmeyer's Textbook
of Polymer Science, 2nd E
d. Pp. 53-57.

The dye ablation method of the present invention can be used to obtain medical images, reprographic masks, printing masks, and the like. The obtained image may be a positive image or a negative image.

As the binder in the recording element used in the present method, any high molecular weight substance can be used as long as it has the above-mentioned molecular weight. For example, cellulose nitrate,
Cellulose derivatives such as cellulose acetate hydrogen phthalate, cellulose acetate, cellulose acetate propionate, cellulose acetate butyrate, cellulose triacetate, hydroxypropyl cellulose ether, ethyl cellulose ether, polycarbonate, polyurethane, polyester, polyvinyl acetate, polystyrene, poly (styrene -Co-acrylonitrile), polysulfone, poly (phenylene oxide), poly (ethylene oxide), poly (vinyl alcohol-co-acetal, such as poly (vinyl acetal), poly (vinyl alcohol-co-butyral) or poly (vinyl benzal) ) or may be used mixtures thereof or copolymers. the binder may be used at a coverage of from about 0.1 to about 5 g / m ^2.

In a preferred embodiment, the high molecular weight binder used in the recording element used in the method is degradable. As used herein, the term "degradable" refers to a binder that rapidly decomposes at the temperature obtained during laser imaging to provide a sufficient amount of gas and volatile fragments, or a decomposition temperature in the presence of a small amount of acid. Is significantly reduced.

[0012] In another preferred embodiment, the infrared absorbing material used in the recording element used in the present invention is a dye used in an image dye layer.

For obtaining laser induced dye ablative images by the method of the present invention, small dimensions are required;
The use of a diode laser is preferred because of its low cost, stability, high reliability, robustness, and ease of modulation. In fact, in order to use any laser to heat a dye-ablative recording element, the element must contain an infrared absorbing material. Examples of infrared absorbing substances include cyanine infrared absorbing dyes described in U.S. Pat. No. 4,973,572 or U.S. Pat. No. 4,948,777.
No. 4,950,640 and 4,950,63
No. 9, No. 4,948,776, No. 4,948,7
No. 78, No. 4,942,141, No. 4,952
No. 552, 5,036,040 and 4,91
Other substances described in 2,083 are mentioned. The laser radiation is then absorbed into the dye layer and converted to heat by a molecular process known as internal conversion. Thus, a useful dye layer composition is:
It depends not only on the hue, transferability and strength of the image dye, but also on the ability of the dye layer to absorb radiation and convert it to heat. The infrared-absorbing dye may be contained in the dye layer itself, or in another layer associated with the dye layer, ie, a layer above or below the dye layer. As mentioned above, the laser irradiation in the method of the present invention is performed through the dye side of the dye ablative recording element. Thus, the method of the present invention can be a single sheet method and does not require a separate receiving element.

For the dye-ablative recording element used in the present invention, any dye can be used as long as it can be ablated by the action of a laser. Particularly good results have been obtained with the following dyes.

[0015]

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Also, US Pat. No. 4,541,830,
No. 4,698,651, No. 4,695,287
No. 4,701,439 and 4,757,04
No. 6, No. 4,743,582, No. 4,769,3
Good results were obtained with any of the dyes described in No. 60 and 4,753,922. The above dyes may be used alone or in combination.
These dyes may be used at a coverage of from about 0.05 to about 1 g / m ^2, and are preferably hydrophobic.

The dye layer of the dye ablative recording element used in the present invention can be coated on a support or printed on the support by a printing technique such as a gravure method.

The support for the dye-ablative recording element used in the present invention can be any material as long as it is dimensionally stable and can withstand the heat of the laser. Such materials include polyesters such as poly (ethylene naphthalate) and poly (ethylene terephthalate); polyamides; polycarbonates; cellulose esters such as cellulose acetate; poly (vinylidene fluoride)
And polyethers such as polyoxymethylene; polyacetals; polyolefins such as polystyrene, polyethylene, polypropylene or methylpentene polymers, and polyimide-amides and polyetherimides. Polyimide is included. The thickness of the support is generally from about 5 to about 200 μm. Also, if desired, US Pat.
An undercoat layer as described in JP-A No. 8 or 4,737,486 may be coated on the support. In a preferred embodiment, the support is transparent.

[0019]

The invention is illustrated by the following examples.

Example 1 Samples were coated using the same dye combination to evaluate the effect of the binder on the differences in melt rheology as indicated by molecular weight.

On a poly (ethylene terephthalate) support having a thickness of 100 μm, the above-mentioned second magenta dye (0.29 g / m ² ) and the above-mentioned second yellow dye (0.16 g / m ² ) When, with the second cyan dye (0.68 g / m ^2), the following cyanine infrared absorbing dye (0.18 g / m ²⁾ and the following binder (0.64
A neutral dye ablative recording element was prepared by applying a dye layer containing g / m ² ) from acetone.

Binder : 1A (control); 1/2 second RS cellulose nitrate obtained from Aqualon (polystyrene equivalent molecular weight is described in Table 1) 1B; 40 second RS cellulose nitrate obtained from Aqualon (polystyrene equivalent molecular weight is 1C; 1000 seconds RS cellulose nitrate obtained from Aqualon (polystyrene equivalent molecular weight is described in Table 1) 1D; 1139 seconds RS cellulose nitrate obtained from Aqualon (polystyrene equivalent molecular weight is shown in Table 1)

IR-1 infrared absorbing dye :

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The recording element was secured to the drum of a diode laser imaging device described in US Pat. No. 4,876,235 with its recording layer facing outward. The laser imaging device consisted of a single diode laser connected to a lens assembly mounted on a translation stage and aimed at the surface of the laser ablative recording element. The diode laser used was Spectra Diode Labs
No. SDL-2430, 800-830 nm
It has an integrated optical fiber for laser beam output in the wavelength range of
50 milliwatts. Optical fiber (core diameter 50
An image was created on the plane of the dye ablative element through a 0.5 × magnification lens assembly mounted on a translation stage with a cleaved surface of μm), resulting in a nominal spot size of 25 μm.

A drum having a circumference of 53 cm is rotated at various speeds, and the imaging electronics are operated to irradiate 415 m of light.
J / cm ² or 980 mJ / cm ² was provided. The translation stage is advanced in small increments laterally of the dye-ablative element by a lead screw rotated by a microstepping motor to reduce the center-to-center distance to 10 μm (945 lines per centimeter or 2 per inch).
400 lines). An air stream was blown over the dye-donor surface to remove the sublimed dye. The average total power measured at the focal plane was 130 mW. The Status A density of the dye layer before imaging is about 3.0 and is 300 revolutions /
And the residual density after writing the D-min patch at min and 150 rpm. Concentration values were obtained with an X-Rite densitometer model 310 (X-Rite).

Table 1 below shows the D-min transmission data at the two irradiation doses.

[Table 1]

The above data show that the use of an element having the binder molecular weight specified in the present invention improves the cleanout properties of the dye.

Example 2 This experiment was performed to demonstrate the same effect as Example 1 using a lower viscosity binder at a lower laser power.

Using the procedure of Example 1, a single color ablative element was fabricated by coating the following binder. 2A (control); 23 cp obtained from Aqualon
s Cellulose nitrate (polystyrene equivalent molecular weight is shown in Table 2) 2B; 6 second RS cellulose nitrate obtained from Aqualon (polystyrene equivalent molecular weight is shown in Table 2) 2C; 18 second RS cellulose nitrate obtained from Aqualon (polystyrene equivalent) 2D; 1055 second RS cellulose nitrate obtained from Aqualon (polystyrene equivalent molecular weight is listed in Table 2).

The elements were imaged at 150 revolutions / minute as in Example 1, except that the average total power measured at the focal plane was 90
mW. The following results were obtained.

[0031]

[Table 2]

The above data also show that the D-min obtained with the element having the binder molecular weight specified in the present invention was significantly improved.

Example 3 This experiment was performed using a series of binder materials with different molecular weights (ScientificPolym).
er Products polystyrene)
This was done to show the effect of using 0.48 g / m ²
And IR-1 of 0.26 g / m ² ,
A coating was prepared from 0.74 g / m ² of the above secondary cyan dye. An element was fabricated using the procedure of Example 1. The elements were imaged at 100 revolutions / minute as in Example 1 and the following results were obtained.

[0034]

[Table 3]

The above data also show that the D-min values obtained using elements having the binder molecular weight specified in the present invention have been significantly improved.

[0036]

The nature of the binder in the dye layer of the above dye ablative recording element for laser ablative imaging, as can be seen from the higher writing speed to achieve a certain minimum density, It has surprisingly been found to significantly affect the desired dye cleanout properties.

Claims (1)

(57) [Claims] 1. A method for forming a single-color dye ablation image with improved D-min including a step of imagewise heating using a laser, wherein the dye ablative recording element includes an infrared absorbing material in combination. A support that carries on its surface a dye layer containing an image dye dispersed in a high molecular weight binder, wherein the laser irradiation is performed through the dye side of the element to remove the ablated image dye material and The method of forming, wherein the image is obtained in a dye ablative recording element, and wherein the high molecular weight binder has a polystyrene equivalent molecular weight of 100,000 or more as measured by size exclusion chromatography.